Production of aromatics from methane

Abstract

A catalyst for the conversion of methane to higher hydrocarbons including aromatic hydrocarbons comprises molybdenum or a compound thereof dispersed on an aluminosilicate zeolite, wherein the amount of aluminum present as aluminum molybdate in the catalyst is less than 2700 ppm by weight.

The invention claimed is: 
     
       1. A process for converting methane to higher hydrocarbons including aromatic hydrocarbons, the process comprising contacting a feed comprising methane with a regenerated catalyst in a reaction zone under dehydrocyclization conditions effective to convert said methane to aromatic hydrocarbons including benzene, wherein said regenerated catalyst comprises molybdenum or a compound thereof dispersed on an aluminosilicate zeolite, wherein said aluminosilicate zeolite is selected from a group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-57 and MCM-22, wherein the amount of aluminum present as aluminum molybdate in said catalyst is less than 2700 ppm by weight; said catalyst characterized by the formation of aluminum molybdate during dehydrocyclization of methane to aromatic hydrocarbons including benzene, wherein the catalyst has been regenerated and prior to regeneration aluminum molybdate was present in the catalyst up to less than 2700 ppm by weight, and wherein said catalyst's exposure during dehydrocyclization and regeneration has been limited to not more than 100 wt ppm molecular oxygen and/or ozone at a temperature not in excess of 500° C. for a cumulative time not greater than 10 hours; wherein the regenerated catalyst, as supplied to the reaction zone, containing less than 270 ppm by weight aluminum present as aluminum molybdate; wherein the catalyst has been regenerated using an ozone-containing gas, said gas optionally further comprising oxygen, at a temperature less than 500° C. 
     
     
       2. The process of  claim 1 , wherein the process is operated so as to maintain the amount of aluminum present as aluminum molybdate in said catalyst at less than 2700 ppm by weight. 
     
     
       3. The process of  claim 1 , wherein the amount of molybdenum or said compound thereof in the catalyst is between about 0.1 and about 20% by weight of the catalyst, based on elemental molybdenum, and wherein the aluminosilicate zeolite comprises ZSM-5 that has a silica to alumina mole ratio between about 14 and about 500. 
     
     
       4. The process of  claim 1 , wherein the process is operated so as to maintain the amount of aluminum present as aluminum molybdate in said catalyst at less than 270 ppm by weight. 
     
     
       5. The process of  claim 1 , wherein the catalyst exposure has been limited to not more than 10 wt ppm oxygen in an oxygen-containing gas at a temperature not in excess of 550° C. for a cumulative time not greater than 1 hour. 
     
     
       6. The process of  claim 1 , wherein the catalyst has been regenerated using an ozone-containing gas, said gas optionally further comprising oxygen, at a temperature less than 300° C.